1. Field of the Invention
This invention relates to improved systems for control of exhaust emissions from gases containing fuel values. In one specific aspect the invention relates to catalytic systems for control of exhaust emissions from internal combustion engines. This invention also relates to passive emissions control devices for fuel-rich internal combustion engines.
2. Brief Description of the Prior Art
Exhaust emissions from small internal combustion engines, such as are used for lawn mowers and small generator sets, are a significant source of atmospheric pollution by hydrocarbons and carbon monoxide. Such engines typically operate fuel-rich and therefore are particularly dirty as compared to an automotive engine without a catalytic converter. Although automotive emissions are now controlled by use of catalytic converters, such conventional devices are not considered feasible for small engine use because of inherently large size, high cost and system complexity relating to the need for air addition. Effective means of suitable size and simplicity are required not only for the reactor itself but also for the addition and mixing of the air needed for oxidation of the exhaust fuel values to carbon dioxide and water.
The present invention meets these needs by providing a passive system for the combustion of the fuel values in the exhaust gases from engines which operate fuel-rich. The system is simple and relatively inexpensive.